The present invention generally relates to the formation of fin field effect transistors (finFET's) in a {100} crystallographic oriented silicon substrate, and more particularly the formation of a quantum well having a conformal epitaxial well on a fin in the {100} crystallographic orientation to increase pFET (hole) mobility while having a negligible impact on nFET (electron) mobility.
In each new generation of semiconductor technology, transistor current decreases due to gate width reduction, mobility degradation of minority carriers and reduction of supply voltage. Reduced transistor current results in deterioration of circuit stability and reduces the speed of circuit operation thereby causing degradation in performance. One of the key parameters determining the mobility of minority carriers is the crystallographic surface orientation on which the channel of the transistor is built. Therefore, the crystallographic orientation of the surface, or the surface orientation of a transistor structure plays a key role in determining the performance of the transistor.
Specifically, the nFET mobility in silicon is high in the {100} crystallographic orientation and significantly decreased in the {110} crystallographic orientation, while the pFET mobility is high in the {110} crystallographic orientation and decreased in the {100} crystallographic orientation of single silicon crystal.